How to access subquery table in the main query with MySQL? - mysql

Question

select m1.id, m1.status, at.view_data, at.view_graph, ta.tag_string
from
access_tbl at, image_campaign_tbl m1
RIGHT JOIN
(select
GROUP_CONCAT(t.name) as tag_string , c.image_campaign_id
from campaign_tags_tbl c,tag_tbl t
where c.tag_id=t.id
$tag_q
group by c.image_campaign_id
) as ta
ON ta.image_campaign_id=m1.id
where
m1.client_id =$client_id
and m1.client_id = at.client_id
$prev_filter
limit $start,$end;
Error message:
in LOGS: DBD::mysql::db selectall_arrayref failed: Unknown column 't.name' in 'where clause' at /home/sakthi/rtads/Project/pm/Image/UI.pm line 2536.**
In Perl Module, I'm passing the same value of $tag_q to the $prev_filter to get the Pagination of filter based on TAGS values in the next page
if ( $prev_filter eq '' ) {
$prev_filter =
$search_clist_q . ' '
. $tag_q . ' '
}
From the error msg, I got the error which I'm doing. Since I'm trying to access the table of subquery in the main query, this error is happening.
So I want to know how to access the tag_string(or)t.name outside the subquery.

Answer 1

First of all, i suggest you to avoid use of old school syntax for jointures (FROM table1, table2,... WHERE table1.column1 = table2.column2 AND ...).
Here is the query that seems to return what you're looking for:
SELECT IC.id
,IC.status
,A.view_data
,A.view_graph
,TA.tag_string
FROM access_tbl A
INNER JOIN image_campaign_tbl IC ON IC.client_id = A.client_id
AND IC.client_id = $client_id
RIGHT JOIN (SELECT CT.image_campaign_id
,GROUP_CONCAT(T.name) AS [tag_string]
FROM campaign_tags_tbl CT
INNER JOIN tag_tbl T ON T.id = CT.tag_id
GROUP BY CT.image_campaign_id) TA ON TA.image_campaign_id = IC.id
WHERE <Your filters here>
LIMIT $start, $end
Hope this will help you.